Process for converting hydrocarbons



Patented Mar. 1, 19932 UNITED STATES PATENT oFFlcE CARBON P. DUBBS, OF WILMETTE, AND JOSEPH` G. ALTHER, 4OIE CHICAGO, ILLINOIS, AS-

SIGNORS 'IO 'UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO,A ILLINOIS, A COB- PORATION on SOUTH DAKOTA rnncnss Fon CONVERTINGHYDROCABBONS Application med .Tune 30,

rlhis invention relates to a process for converting hydrocarbons and refers more particularly to a process in which the percent-V age of distillate remov-ed from the body of the oil is directly controlled by the relative pressures maintained in the heating and vapor zones.

Among its salient objects are to provide a process in which the amount and character of the distillate removed from the oil body is positively controlled by the relative differences in pressure maintained upon the different stages of the process; to provide a process in which the deposition of carbon is practically eliminated from the heating zone and concentrated in the vapor or expansion chamber; to provide a process in which the oil reaction which takes place in the heating tubes is restricted to a cracking or rearrangement of the molecules -of the oil body, whereby the amount of free carbon produced is no greater than can be held in suspension in the oil body anda process in .which the temperature and pressure on the oil in the heat-` ing Zone iscontrolled to maintain the conditions which will produce this type of reaction; to provide a process whereby the precipitation of carbon is concentrated in the vapor chamber; toprovide an improved type of Vapparatus for carrying out this process and in general to provide a process and apparatus of the character referred to.

In the drawings:

Fig. 1 is a side view in elevation of our l apparatus.

Fig'. 2 is a chambers.

Fig. 3 is a header-type cracking tube which may be used in place of the cracking tube shown in the furnace in Fig. 1.

Referring to the drawings, the oil to be treated is introduced through the inlet pipe 1, controlled by a valve 2 to the top of the dephlegmator 8, where it is maintained in pools or stages 4, 5 and 6. The height of the oil in these stages is controlled by the standpipes 4a, 5a and 6a. The oil overflowing from the pool 6 collects in the bottom of the dephlegmator and is drawn olf through the pipe 7 regulated by a valve 8. The oil drawn ofi top plan view of the expansion 1920. Serial N0. 393,065.

through this pipe is chargedto 'the suction side of the pump 9, from which it is injected into the cracking tubes 12 through a charging pipe 10 controlled by a valve 11. The cracking or heating tubes 12V are' mounted in a furnace 13, which is heated by gas burners 14. The heating tubes may either bev a coil type as shownvin Fig. 1, or heating tubes of the header type as shown in Fig. 8.

Referring to the header type construction, the raw oil is introduced through the charging pipe 10a andfafter circulating through the heating or cracking tubes 12a, andheaders 12b, it is drawn of( through'the line 15a. Returning to the construction in Fig. 1, the cracked oil is directed from the heating tubes 'through the line 15 to the expansion chamber 16. The expansion chambers 16 and 17 as shown in Fig. 2 are in duplicate-so `thatvth'e cracked oil as it comes from the heatingtubes may be ldirected to either of the expansion chambersl16 or 17 by manipulating the valves 18 and 19 interposed in the lines 20 and 21 respectively. If it is desired to direct the cracked oil to the vapor or expansion chamber 16, the valve 19 is closed and the valve 18 opened. On the-other hand, if it is preferable to inject the cracked oil to theV expansion chamber 17 the valve 18 is closed, and the valve 19 opened. Residuum drawofs 22,7contr0lled by valves' 23,. are supplied to each of the expansion chambers for drawing ofi1 the heavy residual oil from time to time. y n

The vapors released from the `oil in the expansion lchamber rise through the goosenecks 24 and are directed through the vapor line 25 when released from the vapor chamber Y sa.

the ravv oil in this manner, that part not condensed is taken 0E through the top of the dephlegmator through the gooseneck 32 regulated by valve 33 and is directed to the coil 34 mounted in Water condenser 35. From the Water condenser, the liquid oil and gas proceeds through the line 36 to receiver 37 from Which the distillate may be drawn ott' through the draWot" line 38 regulated by valve 39. A gas relief is provided at 40, which is controlled by a valve 41. A liquid level gauge 42 is provided -in the lowest stage in the dephlegmator and a similar gauge 43 in the receiver.

Pyrometers 44, 45, and46 are supplied at different stages of the. process to ascertain the temperatures inV said stages. Pressure gauges 47, 48, 49, 50 and 51 denote at all times the pressure maintained upon that part of ,the apparatus invvhich the gauge is mounted.

The vapor chambers and vapor lines are heavily lagged as shown at 52 to prevent the lossof heatf b radiation. Trycocks 53 are tapped into tie vapor chamber for ascertaining the height of the oil maintained therein.

By means of this apparatus, a very posi-v tive control may be maintained at all times over thetemperature and pressure to which the oil in the cracking tubes and Vapor chambers is subjected. In practice, We have found that by heating the oil up to a certain temperature-at a corresponding pressure, no carbon is deposited on the Walls of the cracking tube, but the oil at this heat When passing through the expansion chamber under the same pressure at which it Was heated, a rela'- tively small percentage is converted into vapors. Heating the oil higher in order to have a larger percent converted into vapors in the expansion chambers maintained under the same pressure at which the oil is heated, We lind, causes carbon to deposit on the Walls of the-heating tube. In orderto increase the vaporization of the oil in the vapor chamber Without the necessityof heating itto that temperature inthe cracking tubes that Will deposit carbon on the Walls of the cracking tubes under a corresponding pressure, the pressure maintained on the vaporchamber is correspondingly lovver.

In the present invention, I provide a procw ess in which I raise the temperature of the oil in the heating tubes only so high as to cause that degree of cracking Which Will not cause an objectionable amount of carbon to collect inthe heating zone. The heated oil is then directed to the vapor chamber. On enteringth-e Vvapor expansion` chamber, the pressure onthe oil is reduced Which causes a larger percent of the oil to vaporize therein, the percent corresponding to the amount of reduction in pressure. The vapors generated by this reduction of pressure are drawn from this chamber, those vapors of high `boiling points being condensed and returned to the cracking coil for 'further treatment, While the heavier residuum with more or less of t-he carbon, is eliminated from said vapor expansion Vchamber by means of the residue drawois.

By positively controlling the pressures in the heating tubes and vapor expansion chambers,'it is possible to separate Whatever percent of distillate is desired from the body of the oil, Without heating said oil to a temperature that Will cause carbon to deposit on the Walls of the cra-cking tubes. That is, by maintaining one diii'erence in pressure between the heating and vapor zones, We can take off from 20% to 30% of distillate, While by the maintenance of a greater dierence, it is possible to take off higher percentages from the oil body.

To illustratethe eifect the degree of heating has on causing the carbon to deposit on the Walls of the cracking tubes, the following runs Will illustrate the invention. When using a gas oil of approximately 25C Baume gravity at O F. produced from a California oil in the first run, 9287 gallonsof this oil Were treated and said oil was heated to an average temperature in the cracking tubes ot 875O F. From this oil Was obtained 5gg/4% of distillate, by volume, of 47 .2 Baume gravity at 60o F. From this distillate was obtained 43.3% of gasoline by volume, of 61.7 o Baume gravity at 60 F. having an initial boiling point of 120o F. and an end point of 400O F. rI'he heating coils, vapor chambers and condensers Were maintained in free communication, one with another, and Were held under an average pressure of 112 pounds to the square inch. tithe end of the run, thecracking tubes contained a total of 23.65 pounds of carbon figured dry.

Another runmay be described as follows: 8743 gallons of the same gas oil Was used and from it Was obtained 38.54% of distillate of 50.2o Baume gravity at 60O F., and from this distillate was obtained 53.3% by volume of gasoline of 60.4o Baume gravity at 60O F., having an initial boiling point of 100o F. and an end point of 380 F. The average temperature to which the oil Washeated in 'this run in the cracking tubes Was 852?j F. At the end ot the' run there vvas practically no carbon in the cracking tubes. In the latter run, the cracking tubes, vapor chambers and condensers Were in free communication, one with another, and were maintained under 105 pounds average pressure to the square inch.

The quantity yield as shown in the first run, We find, could be obtained by heating the same oil to a temperature in the cracking tubes not exceeding that shovvn in the second run and reducing the pressure on the vapor expansion chamber so as to increase the vaporization of the oil therein so as to yield as large a percentage of distillate as was vaporized in the irst run. The high boiling point fractions are condensed and returne to the heating tubes for further heat treatment as in the two former runs, and thus bring the yield of distillate to equal that produced in the first run and yet shovvno more carbon in the cracking tube than was shown in the second run.

lt will be understood that the temperatures and pressures Will vary according to the oil treated, and the products produced therefrom.

Ne claim as our invention:

A process for cracking hydrocarbon oil comprising passing the oil through a heating coil, subjecting the oil during its lpassage through said coil to such conditions of teinperature and pressure as will effect only that degree of decomposition of the oil in the coil which Will produce an amount of carbon which Will be carried in suspension in the oil, delivering the oil from said coil to an enlarged reaction chamber, effecting a positive reduction in the pressure on the oil prior to admission to said enlarged reaction chambere said positive reduction in pressure being sufcient to effect vaporization of a quantity of oil in said enlarged reaction chamber equal to the quantity of oil vaporized in said enlarged reaction chamber When the oil is raised to a substantially 25 F. higher temperature in the heating coil and no reduction in pressure is effected on the oil in the enlarged re-k action chamber, and in taking olf converted products from sald enlarged reaction chamber.

CARBON P. DUBBS. JOSEPH G. ALTHER. 

